Book: Missing faculty, or Witch at the Academy of the battlemages

All the wonderful that is what usually happens - suddenly, without plan, as if with a light hand of Providence.

Witch - being easily appeased. After a good nasty grievances are instantly forgotten.

Want to guaranteed you noticed, be late. But not too much so as not to miss anything interesting.

If there's a chance somewhere to plunge, witch it always uses!

A good witch will always find a way to circumvent the protection and good to spoil, but only the best witch knows for sure when it's time to do legs.